Direct storage loading for adding data to a database

ABSTRACT

Direct storage loading may be used to add data to a database. New data may be added to a database, using nodes different than a database engine to access a database. The addition of the new data may be assigned to different nodes. The nodes may obtain the data and store the data to storage locations according allocated space in the database by the database engine. The new data can then be made available for access at the database engine.

BACKGROUND

Database systems offer various features of analyzing data. Differenttypes of queries, for instance, can be used to determine behaviors,patterns, trends, states, or other information described in a database.A database, however, can only provide these features for data that isalready part of the database. Adding additional data to a databasesystem to obtain these benefits is not without performance costs to thedatabase system. Therefore, techniques that improve the performance ofadding data to a database system are highly desirable.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a logical block diagram illustrating direct storage loadingfor adding data to a database, according to some embodiments.

FIG. 2 is a logical block diagram illustrating a provider network thatimplements a database service and separate storage service thatimplements direct storage loading for adding data to a database,according to some embodiments.

FIG. 3 is a logical block diagram illustrating various components of adatabase service and separate storage service, according to someembodiments.

FIG. 4 is a logical block diagram illustrating client interactions toadd data to a database using direct storage loading, according to someembodiments.

FIG. 5 is a logical block diagram illustrating interactions todistribute adding different portions of data to a database, according tosome embodiments.

FIG. 6 is a logical block diagram illustrating a data loading cluster,according to some embodiments.

FIGS. 7A and 7B are logical block diagrams illustrating differentassignment schemes for distributing loading of data to a databaseamongst nodes, according to some embodiments.

FIG. 8 is a high-level flow chart illustrating methods and techniquesfor direct storage loading for adding data to a database, according tosome embodiments.

FIG. 9 is a block diagram illustrating a computer system that mayimplement at least a portion of systems described herein, according tosome embodiments.

While embodiments are described herein by way of example for severalembodiments and illustrative drawings, those skilled in the art willrecognize that the embodiments are not limited to the embodiments ordrawings described. It should be understood, that the drawings anddetailed description thereto are not intended to limit embodiments tothe particular form disclosed, but on the contrary, the intention is tocover all modifications, equivalents and alternatives falling within thespirit and scope as defined by the appended claims. The headings usedherein are for organizational purposes only and are not meant to be usedto limit the scope of the description or the claims. As used throughoutthis application, the word “may” is used in a permissive sense (i.e.,meaning having the potential to), rather than the mandatory sense (i.e.,meaning must). The words “include,” “including,” and “includes” indicateopen-ended relationships and therefore mean including, but not limitedto. Similarly, the words “have,” “having,” and “has” also indicateopen-ended relationships, and thus mean having, but not limited to. Theterms “first,” “second,” “third,” and so forth as used herein are usedas labels for nouns that they precede, and do not imply any type ofordering (e.g., spatial, temporal, logical, etc.) unless such anordering is otherwise explicitly indicated.

“Based On.” As used herein, this term is used to describe one or morefactors that affect a determination. This term does not forecloseadditional factors that may affect a determination. That is, adetermination may be solely based on those factors or based, at least inpart, on those factors. Consider the phrase “determine A based on B.”While B may be a factor that affects the determination of A, such aphrase does not foreclose the determination of A from also being basedon C. In other instances, A may be determined based solely on B.

The scope of the present disclosure includes any feature or combinationof features disclosed herein (either explicitly or implicitly), or anygeneralization thereof, whether or not it mitigates any or all of theproblems addressed herein. Accordingly, new claims may be formulatedduring prosecution of this application (or an application claimingpriority thereto) to any such combination of features. In particular,with reference to the appended claims, features from dependent claimsmay be combined with those of the independent claims and features fromrespective independent claims may be combined in any appropriate mannerand not merely in the specific combinations enumerated in the appendedclaims.

DETAILED DESCRIPTION

Various techniques for direct storage loading for adding data to adatabase are described. Database systems may add data to a database invarious ways. For instance, client applications of a database mayperform singleton writes (e.g., structured query language (SQL) “INSERT”statements) or groups of writes (e.g., transactions) to add items, rows,columns, fields, values, or other portions of database data. As suchwrite operations are client application driven, the performance costs ofperforming such writes are expected by the client application. However,for adding large amounts of data (e.g., one or multiple tables, whichmay be very large), adding data to the database may consume significantsystem resources, with great impact on performing other types ofworkloads (e.g., queries or other writes) for the database submitted bythe client application, which may hinder or disrupt the performance ofthe client application (as well as slow performance of the databasesystem overall.

In various embodiments, direct storage loading for adding data to adatabase may be implemented, significantly reducing the performanceimpact of adding data to a database. For example, instead of handling arequest to create a new table from a stored copy of the table in anotherdata store directly, a database engine (e.g., a database managementsystem, query engine, and/or storage engine) may offload the work to agroup of resources that can obtain the new table from the other datastore, reformat or otherwise prepare the table, and then store the tabledirectly, with little or no performance utilization or cost to thedatabase engine. In this way, the database engine can retaincomputational resources (e.g., network bandwidth, processor capacity,Input/Output (I/O) bandwidth, among others) for performing clientapplication requests. Moreover, operators of database systems do nothave to avoid, delay, or schedule adding data to a database at timesthat are least disruptive to other database workloads (e.g., clientapplication requests). Additionally, utilizing separate resources, suchas the data loading clusters discussed below, may allow for performanceoptimizations, such as parallelization, to increase the speed at whichdata can be adding. For instance, the time to load a large table into adatabase could decrease from 1-2 days to 2-3 hours.

FIG. 1 is a logical block diagram illustrating direct storage loadingfor adding data to a database, according to some embodiments. Database120 may be data stored in a data storage system, such as storage service220 in FIG. 2, log-structured storage service in FIG. 3, or otherstorage system or service (e.g., virtual disk or other block-basedstorage system, network attached storage, and so on). Database 120 may,in various embodiments, be separately accessible from database engine110. For instance, the data store for database 120 may implement astorage management application (e.g., data page request processing 361and data management 365 in FIG. 3) that can process access requests towrite to storage locations (or read from them) without directinvolvement of database engine 110. In this way, various operationsperformed to add new data 130 to database 120, such as operations towrite different pages of data in an index structure as discussed belowwith regard to FIGS. 2-7, and 9 can be performed without database engine110 having to perform as much (or any) of the work.

In various embodiments, database engine 110 may perform access requests102 to database 120. For instance, database engine 110 may send or issuevarious requests or commands 104 to a data store for database 120 inorder to perform requests to read data, write data, or remove/deletedata. Database engine 110 and database 120 may implement different typesof database systems, in some embodiments, such as a relational type ofdatabase, non-relational type of database, NoSQL type of database,document type of database, graph type of database, among others.Therefore, the supported types of access requests 102, as well as thetechniques for performing access requests 104, may vary.

Data may be added to database 120 in various ways. For example, asindicated in FIGS. 5 and 8, a request to add data may be received (e.g.,at database engine 110). To perform the request, resources notimplemented by database engine 110 (e.g., at one or more other hostcomputing systems), such as data loading cluster 140, may perform therequest to add new data. To add new data 130, the nodes of data loadingcluster 140, such as nodes 142 a, 142 b, 142 c, and 142 d, may beassigned different portions of the data to obtain and store as part ofnew data 130 (e.g., as discussed below with regard to FIGS. 5-9). Inthis way, the work to add the new data 130 may be shared amongst nodes142 as well as performed in near parallel, increase the speed at whichnew data is added 130.

Nodes 142 may obtain 152 the assigned portions of the data from thesource for data to be added 150. For example, the source may be anotherdata store (e.g., another storage service as discussed below with regardto FIG. 5) or the same data store as storing database 120 (e.g., whenadding a new index structure, such as a secondary index, as new data130). Nodes 142 may perform various transformations upon obtained data,as discussed in detail below. For instance, obtained data may bereformatted from a source format not supported by database engine 110and database 120, sorted, and/or shuffled to other nodes (according tothe assignments). As discussed below, in some embodiments, the new data130 may be stored as (or as part of) an index structure (e.g., ab-tree), with different nodes or portions of the index structure beingwritten to different data pages (e.g., blocks, ranges of blocks, orother storage device allocations in a data store for database 120).

As indicated at 156, the obtained portions of the data 156 may be storedas new data 130 in database 120. In some embodiments, database engine110 may provide information to allocate portions of the database 154 fornew data 130. For instance, database engine 110 may provide data pages(e.g., by identifier) and logical sequence numbers (LSNs) that areassigned to different portions of new data 130 to nodes 142. In otherembodiments—not illustrated—data loading cluster 140 may be able toobtain storage allocations, including data pages allocations, withoutinvolving database engine 110. As indicated at 158, database engine 110may also perform other operations to make the new data available (e.g.,update internal database metadata, complete index structure operations,etc.). Although not illustrated, in other embodiments, one or more nodes142 of data loading cluster 140 may perform the other operations to makethe new database available.

Please note, FIG. 1 is provided as a logical illustration and is notintended to be limiting as to the physical arrangement, size, or numberof components, or devices to implement such features. For instance, thesource for data to be added may be obtained from database 120 (e.g., oneor more tables used to create an index) instead of a separate datastore.

The specification first describes an example of a provider network thatmay implement a database service and storage service, according tovarious embodiments. Included in the description of the examplenetwork-based services are techniques for direct storage loading foradding new data to a database. The specification then describes aflowchart of various embodiments of methods for direct storage loadingfor adding new data to a database. Next, the specification describes anexample system that may implement the disclosed techniques. Variousexamples are provided throughout the specification.

FIG. 2 is a logical block diagram illustrating a provider network thatimplements a database service and separate storage service thatimplements direct storage loading for adding data to a database,according to some embodiments. Provider network 200 may be set up by anentity such as a company or a public sector organization to provide oneor more services (such as various types of cloud-based computing orstorage) accessible via the Internet and/or other networks to clients250. Provider network 200 may include numerous data centers hostingvarious resource pools, such as collections of physical and/orvirtualized computer servers, storage devices, networking equipment andthe like (e.g., computing system 1000 described below with regard toFIG. 9), needed to implement and distribute the infrastructure andservices offered by the provider network 200.

In some embodiments, provider network 200 may implement variousnetwork-based services, including database service(s) 210, a storageservice(s) 220, and/or one or more other virtual computing services 240(which may include various other types of storage, processing, analysis,communication, event handling, visualization, and security services).Database service(s) 210 may implement various types of database systemsand formats (e.g., relational, non-relational, graph, document, timeseries, etc.) and the respective types of query engines to performqueries to those databases. Storage service(s) 220 may include manydifferent types of data stores, including a log-structured storageservice or other storage services, such as object-based storageservices, as discussed below with regard to FIGS. 3-5, in someembodiments and may store database data 222 separately from databaseservice(s) 210 (and thus allow database data to be separately accessiblefrom database service(s) 210).

Clients 250 may access these various services offered by providernetwork 200 via network 260. Likewise network-based services maythemselves communicate and/or make use of one another to providedifferent services. For example, storage service 220 may store databasedata 222 for databases managed by database service 210, in someembodiments. It is noted that where one or more instances of a givencomponent may exist, reference to that component herein may be made ineither the singular or the plural. However, usage of either form is notintended to preclude the other

In various embodiments, the components illustrated in FIG. 2 may beimplemented directly within computer hardware, as instructions directlyor indirectly executable by computer hardware (e.g., a microprocessor orcomputer system), or using a combination of these techniques. Forexample, the components of FIG. 2 may be implemented by a system thatincludes a number of computing nodes (or simply, nodes), each of whichmay be similar to the computer system embodiment illustrated in FIG. 9and described below. In various embodiments, the functionality of agiven service system component (e.g., a component of the databaseservice or a component of the storage service) may be implemented by aparticular node or may be distributed across several nodes. In someembodiments, a given node may implement the functionality of more thanone service system component (e.g., more than one database servicesystem component).

Generally speaking, clients 250 may encompass any type of clientconfigurable to submit network-based services requests to network-basedservices platform 200 via network 260, including requests for databaseservices (e.g., a request to execute a transaction or query with respectto a database, a request to manage a database, such as a request toenable or disable performing queries across different types of queryengines, etc.). For example, a given client 250 may include a suitableversion of a web browser, or may include a plug-in module or other typeof code module that can execute as an extension to or within anexecution environment provided by a web browser. Alternatively, a client250 (e.g., a database service client) may encompass an application, aweb server, a media application, an office application or any otherapplication that may make use of provider network 200 to store and/oraccess one or more databases. In some embodiments, such an applicationmay include sufficient protocol support (e.g., for a suitable version ofHypertext Transfer Protocol (HTTP)) for generating and processingnetwork-based services requests without necessarily implementing fullbrowser support for all types of network-based data. That is, client 250may be an application that can interact directly with provider network200. In some embodiments, client 250 may generate network-based servicesrequests according to a Representational State Transfer (REST)-stylenetwork-based services architecture, a document- or message-basednetwork-based services architecture, or another suitable network-basedservices architecture. In some embodiments, a client of databaseservice(s) 210 may be implemented within provider network 200 (e.g., onanother service 240, such as virtual computing service).

In some embodiments, a client 250 (e.g., a database service client) mayprovide access to a database hosted in database service 210 to otherapplications in a manner that is transparent to those applications. Forexample, client 250 may integrate with an operating system or filesystem to provide storage in accordance with a suitable variant of thestorage models described herein. However, the operating system or filesystem may present a different storage interface to applications, suchas a conventional file system hierarchy of files, directories and/orfolders, in one embodiment. In such an embodiment, applications may notneed to be modified to make use of the storage system service model.Instead, the details of interfacing to provider network 200 may becoordinated by client 250 and the operating system or file system onbehalf of applications executing within the operating systemenvironment.

Client(s) 250 may convey network-based services requests (e.g., arequest to query a database or perform a transaction at a database) toand receive responses from services implemented as part of providernetwork 200 via network 260, in some embodiments. In variousembodiments, network 260 may encompass any suitable combination ofnetworking hardware and protocols necessary to establishnetwork-based-based communications between clients 250 and providernetwork 200. For example, network 260 may generally encompass thevarious telecommunications networks and service providers thatcollectively implement the Internet. Network 260 may also includeprivate networks such as local area networks (LANs) or wide areanetworks (WANs) as well as public or private wireless networks. Forexample, both a given client 250 and provider network 200 may berespectively provisioned within enterprises having their own internalnetworks. In such an embodiment, network 260 may include the hardware(e.g., modems, routers, switches, load balancers, proxy servers, etc.)and software (e.g., protocol stacks, accounting software,firewall/security software, etc.) necessary to establish a networkinglink between given client 250 and the Internet as well as between theInternet and provider network 200. It is noted that in some embodiments,clients 250 may communicate with provider network 200 using a privatenetwork rather than the public Internet. For example, clients 250 may beprovisioned within the same enterprise as a database service system(e.g., a system that implements database service 210 and/or storageservice 220). In such a case, clients 250 may communicate with providernetwork 200 entirely through a private network 260 (e.g., a LAN or WANthat may use Internet-based communication protocols but which is notpublicly accessible).

Services within provider network 200 (or provider network 200 itself)may implement one or more service endpoints to receive and processnetwork-based services requests, such as requests to access data pages(or records thereof), in various embodiments. For example, providernetwork 200 services may include hardware and/or software to implement aparticular endpoint, such that an HTTP-based network-based servicesrequest directed to that endpoint is properly received and processed, inone embodiment. In one embodiment, provider network 200 services may beimplemented as a server system to receive network-based servicesrequests from clients 250 and to forward them to components of a systemwithin database service 210, storage service 220 and/or another virtualcomputing service 240 for processing.

In some embodiments, provider network 200 (or the services of providernetwork 200 individually) may implement various user managementfeatures. For example, provider network 200 may coordinate the meteringand accounting of user usage of network-based services, includingstorage resources, such as by tracking the identities of requestingclients 250, the number and/or frequency of client requests, the size ofdata tables (or records thereof) stored or retrieved on behalf of user,overall storage bandwidth used by users or clients 250, class of storagerequested by users or clients 250, or any other measurable user orclient usage parameter, in one embodiment. In one embodiment, providernetwork 200 may also implement financial accounting and billing systems,or may maintain a database of usage data that may be queried andprocessed by external systems for reporting and billing of client usageactivity. In some embodiments, provider network 200 may be to collect,monitor and/or aggregate a variety of storage service system operationalmetrics, such as metrics reflecting the rates and types of requestsreceived from clients 250, bandwidth utilized by such requests, systemprocessing latency for such requests, system component utilization(e.g., network bandwidth and/or storage utilization within the storageservice system), rates and types of errors resulting from requests,characteristics of stored and requested data pages or records thereof(e.g., size, data type, etc.), or any other suitable metrics. In someembodiments such metrics may be used by system administrators to tuneand maintain system components, while in other embodiments such metrics(or relevant portions of such metrics) may be exposed to clients 250 toenable such clients to monitor their usage of database service 210,storage service 220 and/or another virtual computing service 230 (or theunderlying systems that implement those services).

In some embodiments, provider network 200 may also implement userauthentication and access control procedures. For example, for a givennetwork-based services request to access a particular database, providernetwork 200 may implement administrative or request processingcomponents that may ascertain whether the client 250 associated with therequest is authorized to access the particular database. Providernetwork 200 may determine such authorization by, for example, evaluatingan identity, password or other credential against credentials associatedwith the particular database, or evaluating the requested access to theparticular database against an access control list for the particulardatabase. For example, if a client 250 does not have sufficientcredentials to access the particular database, provider network 200 mayreject the corresponding network-based services request, for example byreturning a response to the requesting client 250 indicating an errorcondition, in one embodiment. Various access control policies may bestored as records or lists of access control information by databaseservice 210, storage service 220 and/or other virtual computing services230, in one embodiment.

FIG. 3 is a logical block diagram illustrating various components of adatabase service and separate storage service, according to someembodiments. Database service 210 may implement one or more differenttypes of database systems with respective types of query engines foraccessing database data as part of the database. In the example databasesystem implemented as part of database service 210, a database enginehead node 310 may be implemented for each of several databases and alog-structured storage service 350 (which may or may not be visible tothe clients of the database system). Clients of a database may access adatabase engine head node 310 (which may be implemented in orrepresentative of a database instance) via network utilizing variousdatabase access protocols (e.g., Java Database Connectivity (JDBC) orOpen Database Connectivity (ODBC)). However, log-structured storageservice 350, which may be employed by the database system to store datapages of one or more databases (and redo log records and/or othermetadata associated therewith) on behalf of clients, and to performother functions of the database system as described herein, may or maynot be network-addressable and accessible to database clients directly,in different embodiments. For example, in some embodiments,log-structured storage service 350 may perform various storage, access,change logging, recovery, log record manipulation, and/or spacemanagement operations in a manner that is invisible to clients of adatabase engine head node 310.

As previously noted, a database instance may include a single databaseengine head node 310 that implements a query engine 320 that receivesrequests, like request 312, which may include queries or other requestssuch as updates, deletions, etc., from various client programs (e.g.,applications) and/or subscribers (users), then parses them, optimizesthem, and develops a plan to carry out the associated databaseoperation(s). Query engine 320 may return a response 314 to the request(e.g., results to a query) to a database client, which may include writeacknowledgements, requested data pages (or portions thereof), errormessages, and or other responses, as appropriate. As illustrated in thisexample, database engine head node 310 may also include a storageservice engine 330 (or client-side driver), which may route readrequests and/or redo log records to various storage nodes withinlog-structured storage service 350, receive write acknowledgements fromlog-structured storage service 350, receive requested data pages fromlog-structured storage service 350, and/or return data pages, errormessages, or other responses to query engine 320 (which may, in turn,return them to a database client).

In this example, query engine 320 or another database system managementcomponent implemented at database engine head node 310 (not illustrated)may manage a data page cache, in which data pages that were recentlyaccessed may be temporarily held. Query engine 320 may be responsiblefor providing transactionality and consistency in the database instanceof which database engine head node 310 is a component. For example, thiscomponent may be responsible for ensuring the Atomicity, Consistency,and Isolation properties of the database instance and the transactionsthat are directed that the database instance, such as determining aconsistent view of the database applicable for a query, applying undolog records to generate prior versions of tuples of a database. Queryengine 320 may manage an undo log to track the status of varioustransactions and roll back any locally cached results of transactionsthat do not commit.

FIG. 3 illustrates various interactions to perform various requests,like request 312. For example, a request 312 that includes a request towrite to a page may be parsed and optimized to generate one or morewrite record requests 321, which may be sent to storage service engine330 for subsequent routing to log-structured storage service 350. Inthis example, storage service engine 330 may generate one or more redolog records 335 corresponding to each write record request 321, and maysend them to specific ones of the storage nodes 360 of log-structuredstorage service 350. Log-structured storage service 350 may return acorresponding write acknowledgement 337 for each redo log record 335 (orbatch of redo log records) to database engine head node 310(specifically to storage service engine 330). Storage service engine 330may pass these write acknowledgements to query engine 320 (as writeresponses 323), which may then send corresponding responses (e.g., writeacknowledgements) to one or more clients as a response 314.

In another example, a request that is a query may cause data pages to beread and returned to query engine 320 for evaluation and processing or arequest to perform query processing at log-structured storage service350 may be performed. For example, a query could cause one or more readrecord requests 325, which may be sent to storage service engine 330 forsubsequent routing to log-structured storage service 350. In thisexample, storage service engine 330 may send these requests to specificones of the storage nodes 360 of log-structured storage service 350, andlog-structured storage service 350 may return the requested data pages339 to database engine head node 310 (specifically to storage serviceengine 330). Storage service engine 330 may send the returned data pagesto query engine 320 as return data records 327, and query engine maythen evaluate the content of the data pages in order to determine orgenerate a result of a query sent as a response 314.

As discussed below with regard to FIGS. 4-7, log-structured storageservice 350 may implement features to perform direct loading of datainto storage nodes for adding data to databases stored in log-structuredstorage service 350. For example, log-structured storage service 350 mayimplement storage manager 370. Storage manager 370 may serve as acontrol plane for storage node(s) 360 and data loading cluster(s) 380.Storage manager 370 may direct, cause or manage different workflows toimplement different features of log-structured storage service 350, suchas failure or maintenance operations with respect to storage nodes 360,the creation or addition of new storage volumes for a database,including assigning storage nodes 360 to store data for differentdatabases. As discussed in detail below, storage manager 370 may alsomanage operations to implement direct storage data loading to add newdata to a database at storage node(s) 370 using data loading cluster(s)380.

In some embodiments, various error and/or data loss messages 341 may besent from log-structured storage service 350 to database engine headnode 310 (specifically to storage service engine 330). These messagesmay be passed from storage service engine 330 to query engine 320 aserror and/or loss reporting messages 329, and then to one or moreclients as a response 314.

In some embodiments, the APIs 331-341 of log-structured storage service350 and the APIs 321-329 of storage service engine 330 may expose thefunctionality of the log-structured storage service 350 to databaseengine head node 310 as if database engine head node 310 were a clientof log-structured storage service 350. For example, database engine headnode 310 (through storage service engine 330) may write redo log recordsor request data pages through these APIs to perform (or facilitate theperformance of) various operations of the database system implemented bythe combination of database engine head node 310 and log-structuredstorage service 350 (e.g., storage, access, change logging, recovery,and/or space management operations).

Note that in various embodiments, the API calls and responses betweendatabase engine head node 310 and log-structured storage service 350(e.g., APIs 321-329) and/or the API calls and responses between storageservice engine 330 and query engine 320 (e.g., APIs 331-341) in FIG. 3may be performed over a secure proxy connection (e.g., one managed by agateway control plane), or may be performed over the public network or,alternatively, over a private channel such as a virtual private network(VPN) connection. These and other APIs to and/or between components ofthe database systems described herein may be implemented according todifferent technologies, including, but not limited to, Simple ObjectAccess Protocol (SOAP) technology and Representational state transfer(REST) technology. For example, these APIs may be, but are notnecessarily, implemented as SOAP APIs or RESTful APIs. SOAP is aprotocol for exchanging information in the context of Web-basedservices. REST is an architectural style for distributed hypermediasystems. A RESTful API (which may also be referred to as a RESTful webservice) is a web service API implemented using HTTP and RESTtechnology. The APIs described herein may in some embodiments be wrappedwith client libraries in various languages, including, but not limitedto, C, C++, Java, C # and Perl to support integration with databaseengine head node 310 and/or log-structured storage service 350.

In some embodiments, database data for a database of database service210 may be organized in various logical volumes, segments, and pages forstorage on one or more storage nodes 360 of log-structured storageservice 350. For example, in some embodiments, each database may berepresented by a logical volume, and each logical volume may besegmented over a collection of storage nodes 360. Each segment, whichlives on a particular one of the storage nodes, may contain a set ofcontiguous block addresses, in some embodiments. In some embodiments,each segment may store a collection of one or more data pages and achange log (also referred to as a redo log) (e.g., a log of redo logrecords) for each data page that it stores. Storage nodes 360 mayreceive redo log records and to coalesce them to create new versions ofthe corresponding data pages and/or additional or replacement logrecords (e.g., lazily and/or in response to a request for a data page ora database crash). In some embodiments, data pages and/or change logsmay be mirrored across multiple storage nodes, according to a variableconfiguration (which may be specified by the client on whose behalf thedatabases is being maintained in the database system). For example, indifferent embodiments, one, two, or three copies of the data or changelogs may be stored in each of one, two, or three different availabilityzones or regions, according to a default configuration, anapplication-specific durability preference, or a client-specifieddurability preference.

In some embodiments, a volume may be a logical concept representing ahighly durable unit of storage that a user/client/application of thestorage system understands. A volume may be a distributed store thatappears to the user/client/application as a single consistent orderedlog of write operations to various user pages of a database, in someembodiments. Each write operation may be encoded in a log record (e.g.,a redo log record), which may represent a logical, ordered mutation tothe contents of a single user page within the volume, in someembodiments. Each log record may include a unique identifier (e.g., aLogical Sequence Number (LSN)), in some embodiments. Each log record maybe persisted to one or more synchronous segments in the distributedstore that form a Protection Group (PG), to provide high durability andavailability for the log record, in some embodiments. A volume mayprovide an LSN-type read/write interface for a variable-size contiguousrange of bytes, in some embodiments.

In some embodiments, a volume may consist of multiple extents, each madedurable through a protection group. In such embodiments, a volume mayrepresent a unit of storage composed of a mutable contiguous sequence ofvolume extents. Reads and writes that are directed to a volume may bemapped into corresponding reads and writes to the constituent volumeextents. In some embodiments, the size of a volume may be changed byadding or removing volume extents from the end of the volume.

In some embodiments, a segment may be a limited-durability unit ofstorage assigned to a single storage node. A segment may provide alimited best-effort durability (e.g., a persistent, but non-redundantsingle point of failure that is a storage node) for a specificfixed-size byte range of data, in some embodiments. This data may insome cases be a mirror of user-addressable data, or it may be otherdata, such as volume metadata or erasure coded bits, in variousembodiments. A given segment may live on exactly one storage node, insome embodiments. Within a storage node, multiple segments may live oneach storage device (e.g., an SSD), and each segment may be restrictedto one SSD (e.g., a segment may not span across multiple SSDs), in someembodiments. In some embodiments, a segment may not be required tooccupy a contiguous region on an SSD; rather there may be an allocationmap in each SSD describing the areas that are owned by each of thesegments. As noted above, a protection group may consist of multiplesegments spread across multiple storage nodes, in some embodiments. Insome embodiments, a segment may provide an LSN-type read/write interfacefor a fixed-size contiguous range of bytes (where the size is defined atcreation). In some embodiments, each segment may be identified by asegment UUID (e.g., a universally unique identifier of the segment).

In some embodiments, a page may be a block of storage, generally offixed size. In some embodiments, each page may be a block of storage(e.g., of virtual memory, disk, or other physical memory) of a sizedefined by the operating system, and may also be referred to herein bythe term “data block”. A page may be a set of contiguous sectors, insome embodiments. A page may serve as the unit of allocation in storagedevices, as well as the unit in log pages for which there is a headerand metadata, in some embodiments. In some embodiments, the term “page”or “storage page” may be a similar block of a size defined by thedatabase configuration, which may typically a multiple of 2, such as4096, 8192, 16384, or 32768 bytes.

As discussed above, log-structured storage service 350 may perform somedatabase system responsibilities, such as the updating of data pages fora database, and in some instances perform some query processing on data.As illustrated in FIG. 3, storage node(s) 360 may implement data pagerequest processing 361, replication log processing 363, and datamanagement 365 to implement various ones of these features with regardto the data pages 367 and page log 369 of redo log records among otherdatabase data in a database volume stored in log-structured storageservice. For example, data management 365 may perform at least a portionof any or all of the following operations: replication (locally, e.g.,within the storage node), coalescing of redo logs to generate datapages, snapshots (e.g., creating, restoration, deletion, etc.), logmanagement (e.g., manipulating log records), crash recovery, and/orspace management (e.g., for a segment). Each storage node may also havemultiple attached storage devices (e.g., SSDs) on which data blocks maybe stored on behalf of clients (e.g., users, client applications, and/ordatabase service subscribers), in some embodiments.

Data page request processing 361 may handle requests to return datapages of records from a database volume, and may perform operations tocoalesce redo log records or otherwise generate a data pages to bereturned responsive to a request. As discussed below with regard to FIG.5, in some embodiments, data to be added to a database may be createdfrom data already stored in the database (e.g., to create a secondaryindex, projection, stored query result, etc.). Data page requestprocessing 362 may handle requests for data from data loading cluster(s)380 directly, without involving database engine head node 310, in orderto obtain data for loading. Data page request processing 361 may alsohandle requests from data loading cluster(s) 380 to store the data to beadded to the database to respective database pages, in some embodiments,as also discussed below.

In at least some embodiments, storage nodes 360 may provide multi-tenantstorage so that data stored in part or all of one storage device may bestored for a different database, database user, account, or entity thandata stored on the same storage device (or other storage devices)attached to the same storage node. Various access controls and securitymechanisms may be implemented, in some embodiments, to ensure that datais not accessed at a storage node except for authorized requests (e.g.,for users authorized to access the database, owners of the database,etc.).

FIG. 4 is a logical block diagram illustrating client interactions toadd data to a database using direct storage loading, according to someembodiments. As discussed above with regard to FIG. 1, loading new datainto a database can be triggered in different ways. In one technique, aclient 410 (e.g., a client application of a database) can send a request(e.g., via an API) to add the new data utilizing direct loading. Forinstance, a request 442 may specify a new table to load, a new secondaryindex (e.g., an alternative index, generated using one or more differentkey values than a primary index used to access one or more tables topoint to rows, records, entries or items in existing table(s) in thedatabase), a projection, or other form of data that can be accessiblewhen stored in the database. Such a request 410 may be specifiedaccording to a language (e.g., a SQL request to create a table orsecondary index) which may include parameters to indicate use of directstorage loading, as well as the information to complete the request,such a location of the source data for the table (e.g., a file path,object identifier, or other storage location for the data), a format ofthe source data, a desired transformation or operation upon the data(e.g., combining data columns, changing data type, adding field valuessuch as a timestamp data, etc.), a table name, secondary index feature(e.g., what is the indexing key value), or other information to completethe request. As noted above with regard to FIG. 1, in some embodimentsthe data to be added may be obtained from multiple different sources andmay be joined or otherwise combined when added to the database. In someembodiments, client 410 may submit the request 442 via a console orother administrative interface (e.g., a command line tool) that utilizesan Application Programming Interface (API) for the request.

As illustrated in FIG. 4, the request may be submitted to databaseengine head node 420, in some embodiments. Database engine head node 420may be similar to database engine head node 310 in FIG. 3, which mayaccess data stored for a database at multiple storage nodes 430 (oflog-structured storage service 350). Database engine head node 420 mayupdate and/or store metadata 444 in storage nodes 430 in order toprepare for and begin allocation of the database for the new table ornew secondary index, in some embodiments. For example, database enginehead node 420 may perform writes to create an invisible table that willnot become marked as available or otherwise visible until loading iscomplete. Storage node(s) 430 may acknowledge the requests 446 todatabase engine head node 420.

Database engine head node 420 may then send a request to storage manager370 to perform a parallel creation for the new table/secondary index asindicated at 448. For example, the request 448 may include informationsuch as the location of the source data, operation parameters,conditions, or inputs to process obtained data, and information forcommunicating with database engine head node 420 and/or storage nodes430 in order to complete the creation of the new table or secondaryindex. Although parallel creation may be performed asynchronously withrespect to client 410 and other workloads of database engine head node420, database engine head node may wait until receiving acknowledgment450 from storage manager 370 that the request will be performed beforeproviding an acknowledgment of the creation request 452 to client 410,in some embodiments. Client 410 can then perform other operations,without being blocked or otherwise waiting on the new able to becompleted (e.g., performing other queries or requests to database enginehead node 420).

As noted above, storage manager 370 for log-structured storage service350 may direct performance of loading new data into a database. FIG. 5is a logical block diagram illustrating interactions to distributeadding different portions of data to a database, according to someembodiments. Storage manager 370 may provision a cluster for adding adata 532, data loading cluster 510. For example, a pool of clustersusable for different loading jobs may be maintained, and pre-configuredto perform loading jobs based on a job request. Storage manager 370 mayselect or assign one of the available clusters from the pool to be dataloading cluster 510, reserving that data loading cluster for a loadingjob until completed. In some embodiments, data loading clusters mayperform more than one loading job as different phases of a loading jobmay utilize different resources (e.g., network bandwidth, memory, CPU,etc.), so availability and assignment may include considering and/orselecting a data loading clusters with capacity to handle anotherloading job in addition to a currently executing job (e.g., a jobexecuting at a different job phase, such as transformation instead ofobtaining data).

Once a provisioned cluster is ready, an indication of readiness 534 maybe sent to store manager 370. Store manager 370 may then send a requestor instruction to start a loading job 536 to data loading cluster 510.The loading job may be specified according to an API that supportsvarious parameters or features of a loading job (e.g., source location,source data format, operations to perform, destination information,access credentials, etc.). In some embodiments, the loading job request536 may be sent as instructions (including programming instructions,such as application code) formatted according to a distributedapplication framework, such as Apache Spark, or as a compiledapplication (generated by storage manager 370) to perform the additionof the data and supplied to cluster 510.

Data loading cluster 510 may begin the loading job, including featuresof distributing or assigning different portions of the job to differentnodes in the cluster, as discussed in detail below with regard to FIGS.6-7B. Nodes of data loading cluster 510 may then begin sending requeststo a source of the data to obtain the data. For example, requests 538 toget data from a file or object in object storage service 520 may beperformed to obtain the data to create a new table from a table storedin object storage service 520, in one embodiment. These requests 538 maybe formatted according to an interface for accessing the table data inobject storage service (e.g., getting files). In another example, dataloading cluster 510 may send requests 540 to storage nodes 430 inlog-structured storage service 350 to obtain data from existing table(s)in order to add a secondary index. Such requests may include queries orother supported operations to retrieve data from storage nodes 430, insome embodiments.

As database engine head node 420 may manage access to the database,database engine head node 420 may perform various operations toallocate, assign, and/or otherwise logically structure storage for thedatabase. For instance, database engine head node may utilize indexstructures, such as b-trees, to order or arrange database data. Nodes orother features of such index structures may be allocated according topages or other schemes at the database engine head node 420 in order tooptimize access and processing of requests to the data using the indexstructures. In order to store data in the database, data loading cluster510 may have to obtain data page assignments (and corresponding LSNs orother information), in some embodiments.

Data loading cluster 510 may perform the various operations and writethe allocated pages with index structure portions (that include dataportions) 544 to storage nodes 430 (e.g. write pages that include b-treeinternal or leaf node data). When writing of pages 544 is complete, dataloading cluster 510 may send a request to database engine head node 420to finalize and make the new data available. Alternatively, in someembodiments, data loading cluster 510 may send an indication of loadingjob completion to storage manager 370 which may send the request todatabase engine head node 420 to make the new data available. Databaseengine head node 420 may perform one or multiple writes to pages tofinalize the index structure 548 (e.g., adding links, adding highernode/parent node pages, etc.) to combine the different portions writtento storage nodes 430. Database engine head node 420 may in someembodiments send a completion indication 550 to storage manager 370(e.g., which may allow data loading cluster to be returned as availableto the pool of clusters).

Different types of distributed data processing platforms may beimplemented as data loading clusters. FIG. 6 is a logical block diagramillustrating an example data loading cluster, according to someembodiments. Data loading cluster 610 may implement a leader node 620(or coordinator, lead worker, etc.) and one or more worker nodes, suchas worker nodes 630 a, 630 b, and 630 c. Leader node 620 may manage theexecution of a loading job sent to data loading cluster 610, such asloading job 602. Leader node 620 may implement load job planning 622,which may parse the loading job request 602 to determine the source datastore location(s), destination, operations, and other features of theloading job. Loading job planning 622 may, among other features,distribute or assign different portions of the data to be addedaccording to different schemes, as discussed below with regard to FIGS.7A and 7B. Leader node 620 can then provide loading assignments 642 toworker nodes 630.

Worker nodes 630 may implement different features to performing assignedportions of a loading job. In some embodiments, worker nodes 630 mayimplement data ingestion, such as data ingestion 632 a, 632 b, and 632c. Data ingestion 632 may include various data readers, scanners,parsers, or other interpreters in order to obtain data stored indifferent formats. Data ingestion 632 may be able to generate and sendrequests to obtain data, such as requests and responses 652 a, 652 b,and 652 c, according to an interface for the source of the data (e.g., aSQL interface or SOAP interface). Data ingestion 632 may performpre-processing to transform obtained data into a format interpretable bydata sorting features, such as data sorting 634 a, 634 b, and 634 c.

Worker nodes 630 may implement data sorting features 634 to obtain theassigned portions of data provided in loading assignments. For example,worker nodes 630 may each ready different portions of source data (e.g.,different files or objects), sort the data into ranges that correspondto different loading assignments and send the data assigned to differentworker nodes 630 via a shuffling technique, as indicated at 644. Forinstance, worker node 630 a may send records that belong to a differentpartition of a new table assigned to worker node 630 c to worker node630 c. In this way, each worker node may not have to read or obtain dataand then filter out data not assigned to that worker node.

Worker nodes 630 may implement loading transformations, such as loadingtransformation(s) 636 a, 636 b, and 636 c. Loading transformations 636may include operations to generate, structure, or otherwise buildassigned portions of data into a structure utilized for storing the newdata in the database. For example, loading transformations 636 mayinclude various techniques to build portions of an index structure likea b-tree to be generated based on the obtained data, including buildingpages to represent different nodes of the b-tree, including links toother pages in the built pages. Loading transformations may include, asindicated at 654 a, 654 b, and 654 c, obtaining pages (and LSNs toindicate a version for the page) in order to use the obtained pages forstoring transformed data. Other loading transformations may includeoperations to add, modify, combine, or filter out portions of data(e.g., specified columns) and transform data into a supported dataformat for the destination database. Worker nodes 630 may write topages, as indicated at 656 a, 656 b, and 656 c, to store the transformeddata, loading that data into the database.

FIGS. 7A and 7B are logical block diagrams illustrating differentassignment schemes for distributing loading of data to a databaseamongst nodes, according to some embodiments. In FIG. 7A, an assignmentscheme may distribute contiguous portions of data to different workernodes. For example, worker node 710 may load two different portions,partition 721 and 722. The data within a partition may be sorted andcontiguous, such as items A to C in partition 721. The data within thesecond partition, partition 722, may also be contiguous (e.g., items Dto F) and the second partition may be contiguous with the firstpartition (e.g., partitions 721 and 722 together include a contiguousrange of items A to F). Similar assignments may be made to other workernodes. Worker node assignment 712 may include a partition 723 withcontiguous items G to I and partition 724 with contiguous items J to L,which together provide a contiguous range of G to L. Worker nodeassignment 714 may include a partition 725 with contiguous items M to Oand partition 726 with contiguous items P to R, which together provide acontiguous range of M to R. Worker node assignment 716 may include apartition 727 with contiguous items S to U and partition 728 withcontiguous items V to Z, which together provide a contiguous range of Sto Z.

Assignment schemes are not without costs. For instance, higher amountsof contiguity may have higher data processing costs (e.g., to shuffledata amongst worker nodes). Less contiguous assignment schemes may beimplemented. For example, in FIG. 7B, an assignment scheme may randomlydistribute portions of data to different worker nodes. For example,worker node 730 may load two different portions, partition 741 and 742.The data within a partition may be sorted and contiguous, such as itemsA to C in partition 741. The data within the second partition, partition742, may also be contiguous (e.g., items V to Z), but not contiguouswith the first partition 741. Similar assignments may be made to otherworker nodes. Worker node assignment 732 may include a partition 743with contiguous items J to L and partition 744 with contiguous items Sto U, which are not together contiguous. Worker node assignment 734 mayinclude a partition 735 with contiguous items G to I and partition 736with contiguous items P to R, which are not together contiguous. Workernode assignment 736 may include a partition 747 with contiguous items Dto F and partition 748 with contiguous items M to O, which are nottogether contiguous.

Other combinations of the above (and/or other) assignment schemes may beimplemented. For example, contiguous portions of the data can be writtentogether or built into an index structure format (e.g., a b-tree). Thus,a b-tree can be built by a worker node for each contiguous portion ofthe data resulting in 4 sub-tree in FIGS. 7A and 8 sub-trees in FIG. 7B.Another technique may start with randomly located, but sorted andcontiguous partitions (e.g., in FIG. 7B). The worker nodes may then sendpartitions to an assigned node which will have a contiguous range of allpartitions at that worker node (e.g., FIG. 7A).

The database service and storage service discussed in FIGS. 2 through 7Bprovide examples of a system that may perform direct storage loading foradding data to a database. However, various other types of data stores(e.g., non-log structured) or other database systems that provideseparate access to database data may implement direct storage loadingfor adding data to a database. FIG. 8 is a high-level flow chartillustrating methods and techniques for direct storage loading foradding data to a database, according to some embodiments. Variousdifferent systems and devices may implement the various methods andtechniques described below, either singly or working together. Forexample, a database engine head node and loading cluster may implementthe various methods. Alternatively, a combination of different systemsand devices. Therefore, the above examples and or any other systems ordevices referenced as performing the illustrated method, are notintended to be limiting as to other different components, modules,systems, or configurations of systems and devices.

As indicated at 810, a request to add data to a database stored in adata store may be received, in some embodiments. The request may be toadd data to be accessible to a database engine in some embodiments. Forexample, the request may specify the data to be added, the source(s) ofthe data (e.g., a data store location either in the same data store or adifferent data store), the destination data format/type (e.g., newtable, secondary index, etc.), transformations to apply (e.g., add,modify, combine, join, filter, aggregate, or delete data), and/orcredentials to obtain the data from a source data store. In someembodiments, the request may be received from a client application, thatutilizes an API, command (e.g., a SQL CREATE table), or other interface.In some embodiments, the request may be received from or triggered byanother application that wrote or stored the data to be added, oranother application that monitors the source data store. For example, adata stream processor, archive system, backup manager, or ExtractTransform Load (ETL) application may send a request to add a table everytime one of those example systems stores a file or object for the tablein the source data store.

As indicated at 820, the addition of different portions of the data maybe assigned to different nodes with access to the data store separatefrom the database engine, in some embodiments. For example, as discussedabove with regard to FIGS. 7A-7B, different assignment schemes for thedata may be used that partition the data in different ways, in order tobalance the workload of loading the data amongst the different nodes.Assignment schemes may be implemented to maximize loading performance,in some embodiments. For instance, depending on the indexing structurefor storing items in the database, the assignment of different items mayadjust. A b-tree structure (or other tree structure, such as a b+ tree)may benefit from utilizing a contiguous ranges of data in assignments inorder to reduce the complexity of combining sub-portions of the indexingstructure together. In embodiments where hash-based indexing isutilized, then assignments may depend upon hash ranges (as opposed toitem value ranges), for instance. In some embodiments, the assignmentmay include obtaining one portion of the data (e.g., a particular datafile or path) and loading another portion determined from differentitems shuffled or sorted amongst the nodes (as discussed above withregard to FIG. 6).

As indicated at 830, the different portions of data may be obtainedaccording to the assignment, in some embodiments. For example, differentqueries, scan operations, read requests, File Transfer Protocol (FTP)copies, or other techniques to obtain the data to add may be performedby the different nodes. In some embodiments, nodes may obtain data, sortthe data, and then shuffle or otherwise redistribute the data amongstthe nodes in order to provide data to the node assigned to load thatdata into the database.

As discussed above, the data may be transformed before storing to thedata store of the database, in various embodiments. For example, datastored in one storage format (e.g., comma separated values (CSV)) may beconverted to another storage format (e.g., InnoDB), in some embodiments.In some embodiments, data may be modified, removed from the data, oradded to the data. In some embodiments, data may written into orincorporated as part of an indexing structure for the database (e.g.,tree structure pages, hash index entries, etc.).

As indicated at 840, the different portions of the data may be stored inthe data store according to allocations in the database for thedifferent portions received from the database engine. For example, eachnode may determine a number of data pages of database storage needed tostore the portion of data. Each node may send a request to the databaseengine according to an API that supports allocation of a specifiednumber of data pages (determined from the determined number of datapages). The database engine may coordinate based on all of the pagerequests for the different portions of the data and assign a number ofpages (and corresponding metadata such as LSNs) to each portion, andprovide back via the API the page information for that node to use tostore the portion of data. In other embodiments, other storageallocation schemes, including utilizing separate storage spaces foradded data may be utilized to allow the different nodes to performallocations in the database.

As indicated at 850, when the different nodes have stored the respectiveportions in the database the different portions of the data availablefor access at the database engine, in some embodiments. For example, thedatabase engine may complete an indexing structure (in the data store)to link the different portions of the data (e.g., sub-trees) to create asingle indexing structure for the added data. A tree based indexingstructure for instance may be combined by a technique where the databaseengine identifies how to link to together different sub-trees into onetree according to that tree's properties (e.g., according to b-treeproperties). Making the data available may also include removing a markor indication that the table is not visible or committed to thedatabase, in some embodiments. In some embodiments, the different nodesmay make the data available for access. A leader node (or other selectednode) may perform index structure completions, updates to databasemetadata to identify the new data as part of the database, and otheroperations to ready the additional data for access (similar to thosediscussed above).

The methods described herein may in various embodiments be implementedby any combination of hardware and software. For example, in oneembodiment, the methods may be implemented by a computer system (e.g., acomputer system as in FIG. 9) that includes one or more processorsexecuting program instructions stored on a computer-readable storagemedium coupled to the processors. The program instructions may beimplement the functionality described herein (e.g., the functionality ofvarious servers and other components that implement the databaseservices/systems and/or storage services/systems described herein). Thevarious methods as illustrated in the figures and described hereinrepresent example embodiments of methods. The order of any method may bechanged, and various elements may be added, reordered, combined,omitted, modified, etc.

FIG. 9 is a block diagram illustrating a computer system that mayimplement at least a portion of the systems and techniques for directstorage loading for adding data to a database described herein,according to various embodiments. For example, computer system 1000 mayimplement a database engine head node of a database tier, or one of aplurality of storage nodes of a separate distributed storage system thatstores databases and associated metadata on behalf of clients of thedatabase tier, in different embodiments. Computer system 1000 may be anyof various types of devices, including, but not limited to, a personalcomputer system, desktop computer, laptop or notebook computer,mainframe computer system, handheld computer, workstation, networkcomputer, a consumer device, application server, storage device,telephone, mobile telephone, or in general any type of computing device.

Computer system 1000 includes one or more processors 1010 (any of whichmay include multiple cores, which may be single or multi-threaded)coupled to a system memory 1020 via an input/output (I/O) interface1030. Computer system 1000 further includes a network interface 1040coupled to I/O interface 1030. In various embodiments, computer system1000 may be a uniprocessor system including one processor 1010, or amultiprocessor system including several processors 1010 (e.g., two,four, eight, or another suitable number). Processors 1010 may be anysuitable processors capable of executing instructions. For example, invarious embodiments, processors 1010 may be general-purpose or embeddedprocessors implementing any of a variety of instruction setarchitectures (ISAs), such as the x86, PowerPC, SPARC, or MIPS ISAs, orany other suitable ISA. In multiprocessor systems, each of processors1010 may commonly, but not necessarily, implement the same ISA. Thecomputer system 1000 also includes one or more network communicationdevices (e.g., network interface 1040) for communicating with othersystems and/or components over a communications network (e.g. Internet,LAN, etc.). For example, a client application executing on system 1000may use network interface 1040 to communicate with a server applicationexecuting on a single server or on a cluster of servers that implementone or more of the components of the database systems described herein.In another example, an instance of a server application executing oncomputer system 1000 may use network interface 1040 to communicate withother instances of the server application (or another serverapplication) that may be implemented on other computer systems (e.g.,computer systems 1090).

In the illustrated embodiment, computer system 1000 also includes one ormore persistent storage devices 1060 and/or one or more I/O devices1080. In various embodiments, persistent storage devices 1060 maycorrespond to disk drives, tape drives, solid state memory, other massstorage devices, or any other persistent storage device. Computer system1000 (or a distributed application or operating system operatingthereon) may store instructions and/or data in persistent storagedevices 660, as desired, and may retrieve the stored instruction and/ordata as needed. For example, in some embodiments, computer system 1000may host a storage node, and persistent storage 1060 may include theSSDs attached to that server node.

Computer system 1000 includes one or more system memories 1020 that maystore instructions and data accessible by processor(s) 1010. In variousembodiments, system memories 1020 may be implemented using any suitablememory technology, (e.g., one or more of cache, static random-accessmemory (SRAM), DRAM, RDRAM, EDO RAM, DDR 10 RAM, synchronous dynamic RAM(SDRAM), Rambus RAM, EEPROM, non-volatile/Flash-type memory, or anyother type of memory). System memory 1020 may contain programinstructions 1025 that are executable by processor(s) 1010 to implementthe methods and techniques described herein. In various embodiments,program instructions 1025 may be encoded in platform native binary, anyinterpreted language such as Java™ byte-code, or in any other languagesuch as C/C++, Java™, etc., or in any combination thereof. For example,in the illustrated embodiment, program instructions 1025 include programinstructions executable to implement the functionality of a databaseengine head node of a database tier, or one of a plurality of storagenodes of a separate distributed storage system that stores databases andassociated metadata on behalf of clients of the database tier, indifferent embodiments. In some embodiments, program instructions 1025may implement multiple separate clients, server nodes, and/or othercomponents.

In some embodiments, program instructions 1025 may include instructionsexecutable to implement an operating system (not shown), which may beany of various operating systems, such as UNIX, LINUX, Solaris™, MacOS™,Windows™, etc. Any or all of program instructions 1025 may be providedas a computer program product, or software, that may include anon-transitory computer-readable storage medium having stored thereoninstructions, which may be used to program a computer system (or otherelectronic devices) to perform a process according to variousembodiments. A non-transitory computer-readable storage medium mayinclude any mechanism for storing information in a form (e.g., software,processing application) readable by a machine (e.g., a computer).Generally speaking, a non-transitory computer-accessible medium mayinclude computer-readable storage media or memory media such as magneticor optical media, e.g., disk or DVD/CD-ROM coupled to computer system1000 via I/O interface 1030. A non-transitory computer-readable storagemedium may also include any volatile or non-volatile media such as RAM(e.g. SDRAM, DDR SDRAM, RDRAM, SRAM, etc.), ROM, etc., that may beincluded in some embodiments of computer system 1000 as system memory1020 or another type of memory. In other embodiments, programinstructions may be communicated using optical, acoustical or other formof propagated signal (e.g., carrier waves, infrared signals, digitalsignals, etc.) conveyed via a communication medium such as a networkand/or a wireless link, such as may be implemented via network interface1040.

In some embodiments, system memory 1020 may include data store 1045,which may be implemented as described herein. For example, theinformation described herein as being stored by the database tier (e.g.,on a database engine head node), such as a transaction log, an undo log,cached page data, or other information used in performing the functionsof the database tiers described herein may be stored in data store 1045or in another portion of system memory 1020 on one or more nodes, inpersistent storage 1060, and/or on one or more remote storage devices1070, at different times and in various embodiments. Similarly, theinformation described herein as being stored by the storage tier (e.g.,redo log records, coalesced data pages, and/or other information used inperforming the functions of the distributed storage systems describedherein) may be stored in data store 1045 or in another portion of systemmemory 1020 on one or more nodes, in persistent storage 1060, and/or onone or more remote storage devices 1070, at different times and invarious embodiments. In general, system memory 1020 (e.g., data store1045 within system memory 1020), persistent storage 1060, and/or remotestorage 1070 may store data blocks, replicas of data blocks, metadataassociated with data blocks and/or their state, database configurationinformation, and/or any other information usable in implementing themethods and techniques described herein.

In one embodiment, I/O interface 1030 may coordinate I/O traffic betweenprocessor 1010, system memory 1020 and any peripheral devices in thesystem, including through network interface 1040 or other peripheralinterfaces. In some embodiments, I/O interface 1030 may perform anynecessary protocol, timing or other data transformations to convert datasignals from one component (e.g., system memory 1020) into a formatsuitable for use by another component (e.g., processor 1010). In someembodiments, I/O interface 1030 may include support for devices attachedthrough various types of peripheral buses, such as a variant of thePeripheral Component Interconnect (PCI) bus standard or the UniversalSerial Bus (USB) standard, for example. In some embodiments, thefunction of I/O interface 1030 may be split into two or more separatecomponents, such as a north bridge and a south bridge, for example.Also, in some embodiments, some or all of the functionality of I/Ointerface 1030, such as an interface to system memory 1020, may beincorporated directly into processor 1010.

Network interface 1040 may allow data to be exchanged between computersystem 1000 and other devices attached to a network, such as othercomputer systems 1090 (which may implement one or more storage systemserver nodes, database engine head nodes, and/or clients of the databasesystems described herein), for example. In addition, network interface1040 may allow communication between computer system 1000 and variousI/O devices 1050 and/or remote storage 1070. Input/output devices 1050may, in some embodiments, include one or more display terminals,keyboards, keypads, touchpads, scanning devices, voice or opticalrecognition devices, or any other devices suitable for entering orretrieving data by one or more computer systems 1000. Multipleinput/output devices 1050 may be present in computer system 1000 or maybe distributed on various nodes of a distributed system that includescomputer system 1000. In some embodiments, similar input/output devicesmay be separate from computer system 1000 and may interact with one ormore nodes of a distributed system that includes computer system 1000through a wired or wireless connection, such as over network interface1040. Network interface 1040 may commonly support one or more wirelessnetworking protocols (e.g., Wi-Fi/IEEE 802.11, or another wirelessnetworking standard). However, in various embodiments, network interface1040 may support communication via any suitable wired or wirelessgeneral data networks, such as other types of Ethernet networks, forexample. Additionally, network interface 1040 may support communicationvia telecommunications/telephony networks such as analog voice networksor digital fiber communications networks, via storage area networks suchas Fibre Channel SANs, or via any other suitable type of network and/orprotocol. In various embodiments, computer system 1000 may include more,fewer, or different components than those illustrated in FIG. 9 (e.g.,displays, video cards, audio cards, peripheral devices, other networkinterfaces such as an ATM interface, an Ethernet interface, a FrameRelay interface, etc.)

It is noted that any of the distributed system embodiments describedherein, or any of their components, may be implemented as one or moreweb services. For example, a database engine head node within thedatabase tier of a database system may present database services and/orother types of data storage services that employ the distributed storagesystems described herein to clients as web services. In someembodiments, a web service may be implemented by a software and/orhardware system designed to support interoperable machine-to-machineinteraction over a network. A web service may have an interfacedescribed in a machine-processable format, such as the Web ServicesDescription Language (WSDL). Other systems may interact with the webservice in a manner prescribed by the description of the web service'sinterface. For example, the web service may define various operationsthat other systems may invoke, and may define a particular applicationprogramming interface (API) to which other systems may be expected toconform when requesting the various operations.

In various embodiments, a web service may be requested or invokedthrough the use of a message that includes parameters and/or dataassociated with the web services request. Such a message may beformatted according to a particular markup language such as ExtensibleMarkup Language (XML), and/or may be encapsulated using a protocol suchas Simple Object Access Protocol (SOAP). To perform a web servicesrequest, a web services client may assemble a message including therequest and convey the message to an addressable endpoint (e.g., aUniform Resource Locator (URL)) corresponding to the web service, usingan Internet-based application layer transfer protocol such as HypertextTransfer Protocol (HTTP).

In some embodiments, web services may be implemented usingRepresentational State Transfer (“RESTful”) techniques rather thanmessage-based techniques. For example, a web service implementedaccording to a RESTful technique may be invoked through parametersincluded within an HTTP method such as PUT, GET, or DELETE, rather thanencapsulated within a SOAP message.

The various methods as illustrated in the figures and described hereinrepresent example embodiments of methods. The methods may be implementedmanually, in software, in hardware, or in a combination thereof. Theorder of any method may be changed, and various elements may be added,reordered, combined, omitted, modified, etc.

Although the embodiments above have been described in considerabledetail, numerous variations and modifications may be made as wouldbecome apparent to those skilled in the art once the above disclosure isfully appreciated. It is intended that the following claims beinterpreted to embrace all such modifications and changes and,accordingly, the above description to be regarded in an illustrativerather than a restrictive sense.

What is claimed is:
 1. A system, comprising: a plurality of computingdevices, respectively comprising at least one processor and a memory,that implement a database service, wherein the database servicecomprises a database engine head node that provides access to a databasestored at one or more storage nodes in a data storage service; thedatabase engine head node, configured to: receive a request to directlyload data into the database; cause the data storage service to load thedata into the database; the data storage service, comprising a dataloading cluster; the data loading cluster, configured to: assign anaddition of different portions of the data to respective nodes in thedata loading cluster; obtain the different portions of the data to addthe data according to the assignment; obtain, from the database enginehead node, respective allocations in the database for the differentportions of the data; store the different portions of the data at theone or more storage nodes according to the respective allocations in thedatabase for the different portions of the data; and wherein thedatabase engine head node is further configured to make the dataavailable for access after the different portions of the data in thedatabase are stored.
 2. The system of claim 1, wherein the request todirectly load data into the database is a request to create a new tablefrom the data stored in another data storage service, and wherein thedata loading cluster is further configured to: before storing thedifferent portions of the data at the one or more storage nodes, modifythe different portions of the data from a first data format supported bythe other data storage service to a second data format supported by thedata storage service.
 3. The system of claim 1, wherein the request todirectly load the data into the database is a request to create a newsecondary index from one or more tables existing in the database, thedata stored in another data storage service, and wherein to obtain thedifferent portions of the data, the data loading cluster is configuredto query the one or more tables at the one or more storage nodes.
 4. Thesystem of claim 1, wherein the different portions of the data are storedinto different portions of an index structure for the database, andwherein to make the data available for access after the differentportions of the data in the database are stored, the database enginehead node is configured to complete the index structure to link thedifferent portions of the index structure together in order to accessthe data.
 5. A method, comprising: receiving a request to add data to adatabase stored in a data store, the added data to be accessible to adatabase engine; assigning an addition of different portions of the datato a plurality of different nodes with access to the data store separatefrom the database engine; obtaining, by the different nodes, thedifferent portions of the data to add the data according to theassignment; storing, by the different nodes, the different portions ofthe data in the data store according to allocations in the database forthe different portions of the data, the allocations received from thedatabase engine; and making the different portions of the data in thedatabase available for access at the database engine.
 6. The method ofclaim 5, wherein the different portions of the data are stored intodifferent portions of an index structure for the database and whereinthe different portions of the data in the database available for accesscomprises completing the index structure to link the different portionsof the index structure together in order to access the data.
 7. Themethod of claim 5, further comprising: before storing the differentportions of the data in the data store, modifying the different portionsof the data from a first data format supported by a source data store toa second data format supported by the data store.
 8. The method of claim5, wherein the request to add the data is sent in response to storingthe data into a source data store from which the data is obtained. 9.The method of claim 5, further comprising: in response to receiving therequest to add the data: provisioning a data loading cluster comprisingthe plurality of different nodes to perform a loading job; wherein theloading job causes performance of the assigning, the obtaining, and thestoring.
 10. The method of claim 5, further comprising: receiving, atthe database engine, requests for a number of pages to store thedifferent portions of the data from the plurality of different nodes;and sending, by the database engine, identified pages to write thedifferent portions of the data as the allocations in the database to theplurality of different nodes.
 11. The method of claim 5, whereinobtaining the different portions of the data to add the data accordingto the assignment comprises: obtaining respective initial portions ofthe data; sorting items in the initial portions of the data; andshuffling the sorted items amongst the different nodes to distribute thesorted items into the different portions of the data assigned to thedifferent nodes.
 12. The method of claim 5, wherein the request to addthe data is a request to create a new secondary index from one or moreexisting tables in the database, wherein the request is received at thedatabase engine, and wherein the data is obtained from the one or moreexisting tables in the database without the database engine.
 13. Themethod of claim 5, wherein the request to add the data is a request tocreate a new table from a table stored in a different data store,wherein the request is received at the database engine, and wherein thedata is obtained from the source data store.
 14. One or morenon-transitory, computer-readable storage media, storing programinstructions that when executed on or across one or more computingdevices cause the one or more computing devices to implement a pluralityof different nodes with access to a data store for a database separatefrom a database engine for the database, wherein the plurality ofdifferent nodes implement: receiving a request to add data to thedatabase stored in the data store, the added data to be accessible tothe database engine; assigning an addition of different portions of thedata to respective ones of the plurality of different nodes; obtainingthe different portions of the data to add the data according to theassignment; obtaining, from the database engine, respective allocationsin the database for the different portions of the data; and storing thedifferent portions of the data in the data store according to therespective allocations in the database for the different portions of thedata, wherein the data is made available for access at the databaseengine after the different portions of the data in the database arestored.
 15. The one or more non-transitory, computer-readable storagemedia of claim 14, wherein the different portions of the data areobtained from a plurality of different source data stores, and wherein,in storing the different portions of the data in the data store, theprogram instructions cause the plurality of different nodes to implementjoining the different portions of data obtained from the plurality ofdifferent source data stores.
 16. The one or more non-transitory,computer-readable storage media of claim 14, wherein the differentportions of the data obtained at the different nodes are differentranges of sorted items that are contiguous within the ranges at thedifferent nodes.
 17. The one or more non-transitory, computer-readablestorage media of claim 14, wherein the one or more non-transitory,computer-readable storage media store further program instructions thatcause the plurality of different nodes to further implement: beforestoring the different portions of the data in the data store, modifyingthe different portions of the data from a first data format supported bya source data store to a second data format supported by the data store.18. The one or more non-transitory, computer-readable storage media ofclaim 14, wherein the one or more non-transitory, computer-readablestorage media store further program instructions that cause theplurality of different nodes to further implement: before storing thedifferent portions of the data in the data store, modifying, adding, ordeleting one or more items in the different portions of the dataaccording to one or more transformations specified in the request to addthe data.
 19. The one or more non-transitory, computer-readable storagemedia of claim 14, wherein, in obtaining the respective allocations inthe database for the different portions of the data, the programinstructions cause the plurality of different nodes to implement:determining a number of pages to store the different portions of thedata; and requesting the number of pages from the database engine. 20.The one or more non-transitory, computer-readable storage media of claim14, wherein the plurality of different nodes are a data loading clusterprovisioned for the database in response to a request from a clientapplication received at the database engine and wherein the request toadd the data to the database is a loading job request.